"It is reasonable to suppose that the goal of a future-mind will be to optimize a mathematical measure of its well-being or achievement, based on its internal state. (Economists speak of 'maximizing utility'', normal people of 'finding happiness'.) The future-mind could discover, by its powerful introspective abilities or through experience, its best possible state the Magic Moment - or several excellent ones. It could build up a library of favourite states. That would be like a library of favourite movies, but more vivid, since to recreate magic moments accurately would be equivalent to living through them. Since the joys of discovery, triumph and fulfillment require novelty, to re-live a magic moment properly, the future-mind would have to suppress memory of that moment's previous realizations.

A future-mind focused upon magic moments is well matched to the limitations of reversible computers, which expend no energy. Reversible computers cannot store new memories, and they are as likely to run backwards as forwards. Those limitations bar adaptation and evolution, but invite eternal cycling through magic moments. Since energy becomes a scarce quantity in an expanding universe, that scenario might well describe the long-term future of mind in the cosmos."
Frank Wiczek (1951 - )
[Big troubles, imagined and real; published in Global Catastrophic Risks, eds Nick Bostrom, Milan M. Cirkovic, OUP, 2008)